The research involves investigation of the general utility of cationic pi-cyclization for synthesis of spirocyclic ring systems. In particular, several stereoselectivity questions will be examined with the objective of developing stereoselective syntheses of spiro (4,5) decane and spiro (5,5) undecane systems. In addition to synthesis of carbocyclic systems, exploratory examination of synthesis of heterocyclic systems by use of heteroatom pi systems will be made.